Chemistry Name : Period:
Worksheet : Molality, molarity and percent problems Date :
A. Review :
1. What is the percent concentration (v/v) of a solution formed by dissolving 20.0 mL of acetone in in 65 mL of ethanol?
2. How many grams of glucose are there in 500.0 mL a 25 % (g/mL) solution of glucose?
3. What is the molarity of a solution formed by dissolving 25.0 g of potassium hydroxide in enough water to form 500.0 mL of solution?
4. What is the molarity of a solution formed by dissolving 18.0 g of sodium nitrate in enough water to form 250.0 mL of solution?
5. How many grams of sodium nitrate are there in 250.0 mL of a .50 M solution of sodium nitrate?
6. How many grams of sodium chloride are there in 30.0 mL of a 1.2 M solution of sodium chloride?
B. Molality problems
7. What is the molality (m) of a solution formed by dissolving 1.2 moles of a solute in .90 kg of solvent?
8. What is the molality (m) of a solution formed by dissolving 3.3 moles of glucose in 1,500 g of water?
9. What is the molality of a solution formed by dissolving 15.0 grams of glucose (molar mass = 180.18 g/mol) in 600.0 grams of water?
10. What is the molality of a solution formed by dissolving 35.0 grams of urea (CH4N2O) in 450.0 grams of water?
11. How many moles of urea are needed to form a 0.20 m solution using 125 grams water?
12. How many grams urea are needed to form a 0.30 m solution of urea using 500.0 grams of water ?
13. How many grams of sucrose (C12H22O11 = 342.34 g/mol) are needed to form a 0.50 m solution of sucrose using 755 grams of water ?
14. How many kilograms of water are needed to form a .50 m solution if 1.0 moles of solute are used?
15. How many grams of water are needed to form a .010 m solution of sucrose if 2.0 moles of sucrose are used?
16. How many grams of water are needed to form a .20 m solution of urea using 25.0 grams of urea(CH4N2O)?
Answers : 1. 24% 2. 125 g 3. 0.891 M KOH 4. 0.847 M NaNO3 5. 11g 6. 2.1 g 7. 1.3 m 8. 2.2 m 9. 0.139 m 10. 1.29 m 11. .025 moles 12. 9.0 g 13. 130 g 14. 2.0 kg 15. 2.0 x 105 g 16. 2,100 g